The present invention relates to an acoustical panel and, more particularly, to an acoustic diffuser panel constructed as an integral unit and configured with wells according to the results obtained from a quadratic-residue number theory sequence.
Acoustic panels having well diffusers are generally conventional. Hansen, for example, discloses in U.S. Pat. No. 4,226,299 (the '299 Patent) an acoustic panel having a parabolic-sinusoidal surface configuration. The panel is formed as a single unit with a plurality of peaks and wells. The panel has curvilinear surfaces. The curvilinear surfaces define equi-depth wells and equi-height peaks. Each well and each peak, respectively, of the panel have equal width. The wells are each filled with flat connecting sections, and sound absorbing portions are centered within each of the wells. Each sound absorbing portion protrudes from its respective well for the height of the peaks.
A deficiency of the acoustic panel of the '299 Patent is that each peak and well of the panel is identical to each other peak and well thereof. Such a uniform configuration is not necessarily optimal for sound diffusion over a typical range of sound frequencies encountered in any given application. More optimal configurations for the typical ranges of frequencies have been mathematically derived, and acoustic diffuser panels have been configured accordingly.
An acoustic diffuser panel which has non-uniform wells according to a mathematically derived design is disclosed by D'Antonio et al., for example, in U.S. Pat. Nos. 4,821,839 and 5,027,920 (the "839 Patent" and "920 Patent", respectively). The acoustic panels are block modular diffusers. The panels are formed with wells of varying depths. The desired well depths for a particular application are, in each instance, determined according to a mathematical formula, referred to as a quadratic-residue number theory sequence. The wells each have corresponding parallel walls and are generally rectangular with 90.degree. angles. The walls of the wells of the acoustic panels are formed from discrete divider elements. Fiberglass inserts of varying thickness are positioned between corresponding walls to partially fill the wells to obtain desired well depths according to the mathematical formula.
A drawback to the acoustic panel disclosed in the '839 Patent is that the panel cannot easily be integrally molded as a single unitary piece. This is the case because, in removal of the panel's parallel side walls from molds, shear forces would typically destroy the materials of the panel and make such removal hard if not impossible. Piecemeal fabrication of the acoustic panels is, therefore, necessary. Such piecemeal fabrication is tedious and costly, relative to fabrication of molded panels. Disadvantages are also exhibited by the acoustic panel of the '920 Patent. In particular, the disclosed acoustic panel is formed from cinder or concrete blocks. Such blocks lack certain desirable acoustic characteristics of molded materials, such as fiberglass. Also, panels of such blocks are likely unwieldy and weighty, limiting the placement of the panels for service and limiting the potential applications for the panels. Like the panels of the '839 Patent, the piecemeal fabrication of the acoustic panels of the '920 Patent is also relatively tedious and costly.
Therefore, what is needed is a system and method for sound diffusion that overcomes these and other problems with conventional acoustic diffuser panels and that provides manufacturing and cost advantages, ready and easy adaptability as a replacement for conventional acoustical ceiling tiles, and improved sound diffusion.